A known class of approaches to material fabrication can be classified as additive manufacturing. Material in various forms, including solid, powder, gel, gas or liquid forms may be processed in such a manner to deposit or lock in material in a target location in space.
Numerous techniques may be utilized to perform additive manufacturing. In extrusion processes materials in wire or filament form are controlled by an extrusion head which may be moved above a work area. The use of multiple extrusion heads and extrusion material may allow for both permanent and temporary structures to be formed. By building the extruded material in layers or in regions complex shapes may be formed in three dimensions. However, the technology is limited by the dimensions of the work space—the ability of the head or heads to move in the two dimensions of a plane and also by the dimension of the ability of the head to move vertically relative to a planar support structure. There may be numerous variations on this form of additive manufacturing.
A different class of additive manufacturing may be classified as Stereolithography. In this class, a light or heat source is used to transform the material in space. In some Stereolithography implementations, the work support plane is submerged in a photoactive or thermo-active liquid and a laser or other light or heat source is rastered across a thin surface layer of the liquid between the support structure and the top level of the liquid. By translating the support structure down a layer, into the liquid the fluent nature of the liquid reforms a thin layer of new unreacted material over the work surface or the previously processed layer.
Versions of Stereolithography may also work with powder formed starting material. The powder may be shaped into a thin layer and then a spatially defined. Lasers may be used to transform portions of the layer into a solidified material. In other examples, other energy sources such as, for example, electron beams, may be used to transform the powder. Various materials including metals, insulators and plastics may be formed into three dimensional shapes by these processing techniques.
A different type of processing occurs when a print head is used to deposit material onto the powder. The deposit may chemically react with the powder or may be an adhesive that consolidates the powder into an adhered location. The prevalence of high resolution printing technology may make this type of additive manufacturing process cost effective.
The field is both established, with versions of additive manufacturing being practiced for decades; and emerging, with new techniques and materials being defined with rapidity. The technology may be currently limited by the dimensions of objects that may be produced and limits on size that are placed by the size of the additive manufacturing equipment. Accordingly, it may be desirable to develop methods and apparatus that may allow additive manufacturing techniques and apparatus to be independently mobile. It may also be desirable to apply the techniques in new manners to the fabrication of advanced building structures and roadways.